South Jersey Pompeii Oven - Am I Doing This Right?

[mintee]

Oh, and I didn't wipe of the mortar on the first few courses, and now I've got a mess.on my hands. Any recommendations on cleaning that off? I was thinking about using a wire wheel brush on my 4" grinder, but part of me thinks the damn mortar is stonger than the brick, and I'll just be removing the brick and leaving the mortar.

[UtahBeehiver]

Couple things to be aware of. I cannot tell from the pics but the centerline of the floor pivot point needs to intersect the horizontal centerline of the brick or else the brick face will not be perpendicular to the center of the dome. The error is cumulative and get worse as you go up in course. Second, the pivot point on your IT is off the floor elevation looks like a couple inches. This will make the height of the dome taller, ie 36" ID diameter oven height at floor level will be 18" plus distance pivot point off the floor level. Not a serious deal but it will affect how you tie into a tapered inner arch. This is why an adjustable IT is important. It does not appear that the IT you are using can be adjusted in or out.

[mintee]

Thanks UtahBeehiver for the info. The centers match up with the brick, I was sure to make that as accurate as possible with my rudimentary IT. Since I'm using a caster, the IT pivot is a little over an inch above the floor, but it's directly into the brick, and not using a plywood standoff. I'm making a 42" oven, so I'm not too concerned about the potiental extra inch. I made the adjustment in the spreadsheet accordingly to calculate the cuts. The IT isn't adjustable, which today I'm understanding why that sucks. I was having a really hard time marking up the outer diameter for the arch. Attached is an image of the inner diameter markings and cuts. (Not sure how the second from the center is so far off, probably gonna have to redo that one.)

The inner diameter arch cuts was totally confusing, and then exactly like you all said, it clicked and made sense. As for the outer diameter, and slope... that's not quite clicking yet. I have some time tomorrow to dig into the forum some more and see if I can understand it better. As of right now, "it maka'no sense."

I did get the 5th chain up, stopping right before the arch. I thought if I laid the 5th up, it would visually make more sense how to cut the arch bricks, but nope...

Gulf Ok, so I'm ready for your words of wisdom on part 2 of these damn arch cuts. Please, lay it on me!

What about cleaning up those old grout lines?

Oh, and what does TDC mean?

[UtahBeehiver]

The slope from the inner dome to the outer dome is the angle from the pivot point to the center of your "L" bracket (assuming the center also hits the center of the brick). TDC is top dead center brick, this will be the longest arch brick. The OD is just your half brick depth dimension. Slope more important than outside dome length (4.5 inches for a 9" brick)

[Gulf]

TDC (top dead center). You have 13 bricks in your flat arch. Brick #7, from left or right is your TDC brick. It should be the longest brick in your arch. I did not do a flat arch but, the theory is still the same. In pic #3 your inner arch brick are resting in formation flat on the table. I would have expected a little more unifomity in the cuts. Are you sure that you had each brick in a straight in line with each of your vertical voussoirs?. That is necessary for the insulated door to fit tight. Again, the TDC brick should be the longest brick in you arch. It may be an optical illusion but, your side bricks appear to be as long or longer than the TDC brick. In pic #1? The brick closest to the camera appears to be protruding a little into the dome to me?

[mintee]

That's weird. Currently the TDC brick is the shortest, at least the way it's cut with just the inner diameter only. Did I somehow do this exactly the opposite way? I'm guessing when I finally figure out how to mark the outer diameter the TDC will actually be the longest.

Because my IT isn't extendable, I'm thinking about just using a chalk line to mark the OD slope. Think that'll work?

[JRPizza]

Best bet is to place the front edge of your arch form forward so that it will be flush with the forward faces of your arch bricks. This will help you keep the arch bricks in line and ensure everything is properly located. In the picture #2 above it does not look like the front edge of the TDC brick is flush with the form, meaning the brick or the form is not moved enough out from center of oven.

[mintee]

Thanks JR, I didn't have the wooden form flush with the front facing bricks. I have the form matched up to the 20" seam that makes the oven inner opening. I had the bricks lined up with the front edge by just using a straightedge. Makes sense to put the form the way you mentioned though.

[UtahBeehiver]

The edge of the form and where the ID line drawn on the brick is also caused by the pivot point being off floor elevation. If you measure the ID at floor level and com p are to the top of the arch form you will find the ID is longer there. This is where an adjustable IT could be shorten, but you could place your pencil back off the "L" at the arch form and trace up

[JRPizza]

I'm not sure if you want to go to any more work, but you could also consider pulling out the brick your IT is attached to and replacing it with a board of appropriate thickness to put your pivot point at floor level. It might take a little trimming of the edge of your caster bracket, but getting it back on location would be relatively straight forward by indexing existing rows side to side and would eliminate the variable of the pivot location. Many of us have copied the wooden brick I first saw used by Gulf and have had good results.

[mintee]

So, about that chalkline to find the outer diameter cut? I'm going back out tomorrow and I'm still now clear as to the best way to make this cut.

[UtahBeehiver]

The chalk line from the pivot point is best used for defining the slope of the top cut not the outside diameter. So at the intersection point of the bottom slope (which you have already done) and the top slope defined by the chaulk line, the OD will your half brick dimension, as I mentioned before, the slope is more important than the OD determination. Again, I emphasize that each brick is different each side of TDC, so don't cut all the arch bricks the same, measure on both side of the brick, the cuts are not linear but skewed from side to side on each brick. If you look at pic that JR attached you can see this clearly.

[JRPizza]

So, about that chalkline to find the outer diameter cut? I'm going back out tomorrow and I'm still now clear as to the best way to make this cut.

There is no OD cut on an arch brick per se, there is a cut on the lower half of the brick (lower left in my picture) to match the ID of the oven, and an angled cut along the top of the brick (upper left in the pic) for a dome brick to rest on as you cover your arch. Ignore the diagonal line drawn in the upper right of the picture - I was still figuring out how to make the cuts and that line shouldn't be there
The upper cut should have enough angle that the dome brick above the arch can not only sit in it's proper orientation (outward face perpendicular to the arm of the IT) but also enough room for some mortar. Some builders have done all their arch cuts and compled their arch before they start the dome, but I found it easier to cut those top surfaces as I completed each row and saw for sure where the dome brick was going to intersect the arch.

[mintee]

So, long day, not a ton of production, but I think my brain is starting to line up, pun intended. Here's the what I hope to believe is correct. (I'll post the other photo in the next post as I keep getting file size errors, even though the file size is small enough)

I really can't thank you guys enough for your patience. I would have given up on me a couple posts ago, hah!

[mintee]

Ok, the forum doesn't like my other photo, so here's a direct link.

https://photos.app.goo.gl/VNazA9NMJjUmyQom7

What's making me choose line 2 over line 1 and 3 if the OD truly doesn't matter? It's beginning to click, but I'm 99% sure the L1 and R1 weren't cut properly. JRPizza I totally agree with the cut them as they line up, I'm clearly not smart enough to build an arch alone.

Also, I plan on receeding the IT down tomorrow (or the next time the wife let's me spend time on it) using a 1/2" "Wooden Brick". UtahBeehiver it took a while, but it makes sense to me now how the extra 1.5 inch can mess with the dimensions of the arch (and dome).

I also bought a wirewheel for my grinder to remove some of the bad mortar on the first 4 courses, and that's proving to be a task. Check the other photo in my signature to see.

I'm 50% certain that something is majorly wrong and I'm looking forward to finding out what so I can fix it ASAP!